1. Field of the Invention
The present invention relates to a multi-lens image pickup apparatus having plural image pickup systems.
2. Related Background Art
In a camera having a single image pickup system and single image display means, the image picked up by the image pickup system is conventionally stored in a video memory (VRAM) provided in the camera. Thereafter the controller of the image display means reads, from the VRAM, the pixel values of the points constituting the image and display the image on the image display means. In such single-eyed camera system, the image picked up by the image pickup system can be simply entered in the VRAM, so that a moving image can also be displayed on the image display means with an image pickup rate same as that for the still image.
On the other hand, as a system for picking up and displaying a stereoscopic image, there is conventionally known, for example, a stereoscopic television apparatus disclosed in the Japanese Patent Laid-open Application No. 62-21396. In such stereoscopic image pickup and displaying system, a set of images having a parallax are basically picked up with plural cameras and are displayed on an exclusive stereoscopic image display device to provide a stereoscopic image to the photographer.
In such stereoscopic image pickup/displaying system, as the cameras for image pickup are separated from the stereoscopic display device for stereoscopic image display, the photographer is unable to constantly observe the stereoscopic image, so that it is difficult to adjust the cameras under the observation of the image.
Also in case of image pickup while the cameras are moved, there are required operations of, at first, picking up the image while the display is detached and then editing the image while the image is displayed, so that the stereoscopic image cannot be picked up in a simple manner.
Also for displaying a stereoscopic image, there is known a method of forming a right-eye image and a left-eye image of different polarized states and separating the left and right images with polarizing spectacles, and, for forming such different polarized state, the display device is provided with a liquid crystal shutter for switching the polarized state in synchronization with the field signal of the displayed image, whereby the observer wearing the polarizing spectacles observes the left and right images with respective eyes, one at a time on time-shared basis, the stereoscopic observation is enabled. This method, however, is associated with a drawback that the observer has to always wear the polarizing spectacles.
On the other hand, for stereoscopic image display without such polarizing spectacles, there is known a method of providing a lenticular lens in front of the display, thereby spatially separating the image entering the left and right eyes. FIGS. 21A and 21B show a conventional stereoscopic image display method employing the lenticular lens. Referring to FIG. 21A showing a view seen from the top of the observer, there is shown a display pixel unit 60 of a liquid crystal display, of which the glass substrates, color filters, electrodes, polarizing plates, rear light source etc. are omitted. The display pixel unit 60 is composed of apertures 61 constituting pixels and provided with color filters, and a black matrix 62 separating the pixels. The apertures 61 are arranged as shown in FIG. 21B.
On the surface of the liquid crystal display, there is provided a lenticular lens 63 consisting of cylindrical lenses each having a semicircular cross section and extending in a direction perpendicular to the plane of the drawing, and the display pixel unit 60 of the liquid crystal display is positioned at the focal plane of such lenticular lens. On the display pixel unit 60, right-eye images (R) and left-eye images (L) of stripe shape are alternately arranged in such a manner that a pair of such images corresponds to a pitch of the lenticular lens 63, and are optically separated by the lenticular lens 63 to the right eye Er and the left eye El of the observer whereby the stereoscopic observation is rendered possible.
In FIG. 21A there are illustrated spatial areas where the right-eye image and the left-eye image can be respectively observed by the cylindrical lens at the central part of the display. For each of other cylindrical lenses, the spatial areas are similarly separated at the left and at the right for the respective eyes of the observer, whereby the left and right images are uniformly separated and observed over the entire image area.
In this method, the horizontal resolving power of the image display device is reduced to 1/2 since the stripe images, synthesized from the two parallax images, have to be displayed.
On the other hand, the Japanese Patent Laid-open Application Nos. 5-107663 and 7-234459 disclose stereoscopic image display devices without loss of the resolving power. FIGS. 22A to 22C illustrate the configuration and the display method of the stereoscopic image display device disclosed in the Japanese Patent Laid-open Application No. 5-107663. This device is composed of a light directionality switching device 72 consisting of a matrix planar light source 70 and a lenticular lens sheet 71, and a transmissive display device 73 (FIG. 22A). When stripe-shaped light sources 70R for the right eye (cf. FIG. 22B) are turned on, an image 73R for the right eye is displayed in synchronization in an odd frame (or field) (cf. FIG. 22C), and, when stripe-shaped light sources 70L for the left eye are turned on, an image 73L for the left eye is displayed in synchronization in an even frame (or field). Since all the pixels are used in each of the even and odd frames (or fields), the pixels need not be split and the horizontal resolving power is not deteriorated.
In the aforementioned conventional example, however, in case of displaying paired images picked up with a multi-lens image pickup apparatus, such paired images cannot be simultaneously written into the VRAM.
In order to overcome such drawback, there is known a method of writing an image into a half area of the VRAM while temporarily retaining the other image in another memory, and, after such image writing into the VRAM, transferring the other image from such memory to the VRAM, thereby displaying the image pair on single image display means. In such method, however, since the image displayed on the image display means is switched, there results a drawback that the display rate becomes slower in comparison with the image pickup rate.
On the other hand, the conventional configuration employing the lenticular lens on the surface of the liquid crystal display is associated with drawbacks that the image quality is deteriorated by the surface reflection from the lenticular lens surface and that the black matrix of the liquid crystal display is observed as moire fringes.
Also in the stereoscopic displaying method by displaying the right-eye image and the left-eye image on time-shared basis, the switching of the images has to be conducted at a high speed in order to prevent the flickering phenomenon.
Isono et al. reported, in xe2x80x98Conditions for stereoscopic observationxe2x80x99, Journal of Television Association, Vol. 41, No. 6 (1987), pp549-555, that stereoscopic observation could not be obtained with the time-shared method of a field (frame) frequency of 30 Hz.
Also the limit frequency at which the flickering is not sensed when both eyes are alternately opened and closed (called critical fusion frequency or CFF) is about 55 Hz, indicating that the field (frame) frequency has to be at least 110 Hz in terms of the flickering. Consequently there is required a transmissive display device capable of high-speed display.
Also in such stereoscopic image systems, there has not been considered the compatibility with the two-dimensional image which is dominant in the current image pickup systems. Stated differently, the stereoscopic image system and the two-dimensional image system have been constructed as separate independent systems. Consequently, the individual user wishing to pick up a stereoscopic image has to construct the system anew, involving cumbersome operations.
A first object of the present invention is to provide a multi-lens image pickup apparatus capable of picking up not only a panoramic or stereo image but also an ordinary image and enabling display of ordinary, panoramic and stereo images.
A second object of the present invention is to provide a multi-lens image pickup apparatus capable, in displaying paired images picked up with the multi-lens image pickup apparatus simultaneously on an image display unit, of displaying a moving image with a display rate equal to the image pickup rate.
A third object of the present invention is to provide a multi-lens image pickup apparatus capable, in reproducing the picked-up image, of improving the resolution of the stereoscopic image without increasing the display rate (frame rate) required for the image display unit, by displaying a thumbnail image thereon.
The above-mentioned objects can be attained, according to a preferred embodiment of the present invention, by a multi-lens image pickup apparatus provided with plural image pickup systems and an image display means adapted to store plural images respectively picked up with the plural image pickup systems in image memory means after synthesis into an image and to display the stored image on the image display means, the camera comprising horizontal compression means for compressing the plural picked-up images in the horizontal direction, selection means for selecting the input of the plural image signals and outputting thus selected image signal to the image display means thereby compressing the plural images in the vertical direction, and memory control means for storing the compressed plural images in the image memory means in such a manner that the plural images compressed in the horizontal and vertical directions are displayed in arranged manner.
Also the above-mentioned objects can be attained, according to a preferred embodiment of the present invention, by a multi-lens image pickup apparatus provided with plural image pickup systems and an image display means capable of displaying a stereoscopic image, and capable of synthesizing plural images respectively picked up with the plural image pickup systems thereby displaying a stereoscopic image or a panoramic image on the image display means, the camera comprising display control means for displaying, on the image display means, a thumbnail image corresponding to the stereoscopic or panoramic image.
Still other objects of the present invention, and the features thereof, will become fully apparent from the following description which is to be picked up in conjunction with the attached drawings.